<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</head>
<body>
    <div id="app">
        {{msg}}
        <p v-text="msg01"></p>
        <button v-on:click="mis">-</button>
        <input type="text" v-model = "msg01">
        <button v-on:click="add">+</button>
    </div>

    <script>
        let vm = new Vue({
            el:"#app",
            data: {
                msg: 'Hello~',
                msg01: 0,
                msg02: '12345'
            },
            methods: {
                add() {
                    this.msg01++;
                },
                mis() {
                    this.msg01--;
                }
            }
        })

    </script>
</body>
</html>